Hmm, I don't know if there has been a thread done on this or not. You'll have to see what the others say about that. ANYWAY I think I should get back to the topic...
Personally, my favorite stage is Norfair.
That stage hasn't let me down once yet. Stages that consist of platforms FTW! I can shark SO many people here reasonably well while defending myself by grabbing on those platforms to gain invincibility frames. Then I repeat the process while avoiding their attacks. Also, the lava helps me get some of KO's too because I can just knock my opponent into the lava and get a KO 75% of the time depending on their percentage. If it doesn't KO them well, extra damage build up is always helpful.
I'm starting to work on liking Brinstar too. So far it's going well for me as I am utilizing more and more of Kirby's tricks on this stage. ^_^ I can catch many people off guard with that stone glitch on this stage.
Also, acid damaging my opponents = win. If they don't get hit by the acid, I'll attack them when they retreat to the top of the platform. Also, both stages help against chain grabbers and Brinstar helps me against some projectile users and I can refresh my moves when I attack those 'columns'. I like Rainbow Cruise too, but I don't like it as much as Norfair or Brinstar. RC probably my third favorite out of Kirby's good stages. I feel uncomfortable on Jungle Japes and I also feel awkward being there. Therefore, I don't go on it often.
Both Brinstar and Norfair are my favorite Kirby stages overall. I think RC is good too, but not as good as Norfair or Brinstar IMO.
Hmm...I didn't think I'd ever find someone who likes going on Pirate Ship with Kirby. Well, select what you think will benefit you however IMO, there are better Kirby stages than that. Also Kirby can't gimp his opponents because of the water which means you'll have to rely on your KO moves to get them off stage. Just a tip, don't take Ike here. He will destroy Kirby on that stage.